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Not sure why this did not post earlier so this is try #2

Rebuilding a Sears mower engine Model 143.016000, Family YTPXS.1851BA which has been identified as a Tecumseh LEV 115-3600033D and need some help.
Have a really bad oil leak out of the crankshaft seal part 75 in diagram (https://www.searspartsdirect.com/model-number/143006700/0247/1503500.html) and am wonder if when I replace the seal is it set flush to the bottom of the case or is it set down inside the case? Does this make any sense? I have the manual and it says " CHECK TO
SEE IF THE SEAL IS RAISED OR RECESSED. WHEN INSTALLING A NEW OIL SEAL, TAP IT INTO POSITION GENTLY UNTIL IT IS SEATED INTO ITS BOSS. SOME SEALS ARE NOT POSITIONED FLUSH TO THE CYLINDER COVER. Sorry for all caps I am using cut and paste here. I trouble is the seal was replaced about a year ago and was flush to bottom of the case but I am now not sure if that is correct because to oil leakage started after the seal replacement.

I set the seal flush to the case but the is room to seat it a bit lower but I would rather not mess up the seal and gasket by installing it wrong. Any ideas would help.
Tom

i use a small amount of clear silicone on index finger & apply to outside diameter of oil seal then use a deep well socket, if you have room, & strike socket until seal is flush with housing. first inspect crankshaft for burs, pits, etc. housing as well.

It is a bit late now but for the benefit of others who might stumble onto this thread, always measure the depth of the oil seal BEFORE you pull it out.
So now you will have to remember if there was a hole in the side of the hole where the oil seal fits.
If there was one you must be careful not to push the seal down so far that the hole is blocked .
Usually there is a small chamfer in the oil seal hole and the seal goes down to the edge of the chamfer.
Typically about 1/16 " below the lip.

Thank you Bert and Mark, There is a groove like a key way slot cut in the case along where the seal goes, will double check everything and most likely have to order a new seal if it is installed wrong. It was flush to the outside edge of the case but that left about a 1/8 inch gap between the seal edge and the case.
Tom

Pumper54 said:

Thank you Bert and Mark, There is a groove like a key way slot cut in the case along where the seal goes, will double check everything and most likely have to order a new seal if it is installed wrong. It was flush to the outside edge of the case but that left about a 1/8 inch gap between the seal edge and the case.
Tom

Click to expand...

Not too sure what you are saying but some engines have a drain hole in the case to prevent debris filling up the cavity and turning it into a grinder.
If the shaft has a prominent groove in it you will need to fit a Speedi sleeve or a readi sleeeve to restore the running surface.

bertsmobile1 said:

Not too sure what you are saying but some engines have a drain hole in the case to prevent debris filling up the cavity and turning it into a grinder.
If the shaft has a prominent groove in it you will need to fit a Speedi sleeve or a readi sleeeve to restore the running surface.

Click to expand...

It appears to be a milled slot like a key way in the shaft. I will try to post a picture later today to show you what I am referring to.

Tom

You can not run a seal over a slot , for obvious reasons.
Some crabkshats have 2 key way slots one near the cases & one near the end of the shaft.
When I fit a seal that qill come into contact with a slot during assembly, I put twp turs of cling film around the shaft to stop the edges of the keyway cutting the lsealing lip on the seal.
Plus copious quantities of rubber grease or petrolium jelly.

picture of the out put shaft from the engine I did try to clean up somr of the roughness (rust) on it but am waiting on some parts before I spend time with it.


In this picture you can see the slot I was referring to and also right at the end of it is a hole which I believe is the oil return passage you were talking about.

bertsmobile1 said:

You can not run a seal over a slot , for obvious reasons.
Some crabkshats have 2 key way slots one near the cases & one near the end of the shaft.
When I fit a seal that qill come into contact with a slot during assembly, I put twp turs of cling film around the shaft to stop the edges of the keyway cutting the lsealing lip on the seal.
Plus copious quantities of rubber grease or petrolium jelly.

Click to expand...

I really like the idea of the cling film around the shaft. Will try that if it looks like the seal and shaft don't want to play nice together.
Tom

Ok now the head is around it.
The slot is the oil feed and the hole is the oil return
Is there a step on the inside of the hole at the other end ?

Usually you'd want to put the sump plate on first, then put the seal over the shaft and into the sump. Tape or something over the shaft keyways won't let the sump go over the shaft, the seal will give enough for the seal to slide on.

Bert,
Yes Sir there is a lip that keeps the seal from covering the oil return hole.
Tom